SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a611e3f08480b653343e5c5ad2ef90e31f043f3451043fa4d67fa6a59fa2546e' 
  AND token = '2DDC+kM9N2d0QvoP0XiB5xiS1kmSZTpDcY5K1wHoybk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}